Medical dressings are popular for use on anatomical wounds to protect the wounds and promote healing, at catheter sites to secure and stabilize the catheters, as surgical drapes to define a sterile field and in diverse medical procedures to perform various other functions. Many medical dressings are of minimal thickness to provide great flexibility allowing the dressings to flex and conform to the irregular shapes and contours of anatomical and other surfaces to which they may be applied and to permit moisture to penetrate the dressings to prevent maceration of the skin. Such dressings typically include a thin backing sheet or film, a layer, surface, or body of adhesive carried by the backing sheet and a removable release liner disposed over the adhesive. Upon removal of the liner, the dressing is flexible, conformable, supple, limp or flimsy due to the minimal thickness thereof such that there is a tendency for the dressing to wrinkle, buckle, fold or turn over on itself. Accordingly, handling of the dressing and application of the dressing to a surface can be difficult, tedious and can result in portions of the dressing becoming stuck together or the dressing being improperly applied.
Various delivery systems for medical dressings have been proposed to facilitate handling and application of the dressings. Many proposed delivery systems are part of the medical dressings themselves, and U.S. Pat. Nos. 4,413,621 to McCracken et al, 4,485,809 to Dellas, 4,664,106 to Snedeker, 5,160,315 to Heinecke et al and RE 33,353 to Heinecke and European Patent 0,051,935 are illustrative of such medical dressing delivery systems. Some of the disadvantages of prior art medical dressing delivery systems include complexity, increased number of parts, increased material and manufacturing costs, intricate handling and application protocols, the need for multiple release liners and touching of or other contact with the adhesive during handling and/or application with concomitant impairment of cleanliness and adhesion. Some prior art medical dressing delivery systems utilize a release liner having a central window portion and a continuous outer frame portion with the central window portion being removable separately from the backing sheet to expose a face of the backing sheet carrying the body of adhesive. Upon removal of the central window portion, the support portion remains attached to the backing sheet to rigidify and support the dressing and prevent or minimize wrinkling, folding and buckling of the dressing during handling and application of the dressing on a surface. Once the dressing has been applied to the surface by placing the exposed face of the backing sheet thereagainst, the support portion is detached or removed, with or without a section of the backing sheet, to complete the application.
A major disadvantage is that there is no edge portion of such dressings which has the desired conformability of the dressing itself due to the intentional rigidity of the continuous frame. For example, the design in EP 51,935 provides a second release liner overlying the backing layer wherein the second release liner is defined by a central window and a frame. A first release liner overlying the skin-contacting adhesive surface can be removed as well as the central window portion of the second release liner prior to application. However, the caregiver typically touches part of the skin-contacting region during application and therefore cleanliness is compromised. Also, since the frame intentionally provides a more rigid periphery, the conformal nature of the dressing, especially when being used over a catheter entry point, is decreased. That is, the continuous frame makes it difficult to secure the dressing sealably around the catheter. Further, the caregiver is unable to see all that is being covered by the final dressing since the frame covers the periphery of same.
Another continuous periphery or "window frame" design is disclosed in U.S. Pat. No. 4,485,809 to Dellas. The '809 patent utilizes only the release liner which overlies the skin-contacting adhesive surface and which includes a central window portion and a continuous peripheral frame portion. The dressing further includes perforations in the dressing backing and adhesive in alignment with the central window portion. Upon removal of the central window portion of the release liner, the dressing is applied and the frame and continuous peripheral portion of the dressing itself are removed by tearing at the perforations. This design still suffers from a lack of conformability of at least one edge for sealing a catheter site and also requires a considerable force and tugging to begin the periphery removal. Periphery removal for such a continuous frame design can cause edge roll-up and dressing shift or displacement